c#执行cmd命令不工作

谁能建议为什么下面的代码不返回系统日期?

 ProcessStartInfo cmdInfo = new ProcessStartInfo("cmd.exe", "net time ''192.168.221.1");
            cmdInfo.CreateNoWindow = true;
            cmdInfo.RedirectStandardOutput = true;
            cmdInfo.RedirectStandardError = true;
            cmdInfo.UseShellExecute = false;
            Process cmd = new Process();
            cmd.StartInfo = cmdInfo;
            var output = new StringBuilder();
            var error = new StringBuilder();
            cmd.OutputDataReceived += (o, e) => output.Append(e.Data);
            cmd.ErrorDataReceived += (o, e) => error.Append(e.Data);
            cmd.Start();
            cmd.BeginOutputReadLine();
            cmd.BeginErrorReadLine();
            cmd.WaitForExit();
            cmd.Close();
            var s = output;
            var d = error;

输出

{Microsoft Windows [Version 6.1.7601]Copyright (c) 2009 Microsoft Corporation.  All rights reserved.D:'TEST'TEST'bin'Debug>}

ProcessStartInfo cmdInfo = new ProcessStartInfo("cmd.exe", "/C net time ''''192.168.221.1");